Extreme pressure lubricant



United States Patent v 7 2,726,209 EXTREME PRESSURE LUBRICANT MortonFainman, Chicago, Ill., assignor to Standard Oil Company, Chicago, 111.,a corporation of Indiana.

' N0 Drawing. Application August 31, 1954, Serial No. 453,435

7 Claims. (Cl. 25233.6)

This invention relates to improvements in lubricants and, in particular,to improvements in extreme pressure lubricants adapted for use onbearingsurfaces which are subjected to high pressures and high rubbingvelocities during use. In a more particular sense, the invention relatesto the method of preparing such lubricants.

High unit pressures which are encountered frequently in devices employedfor transmission of power, such as hypoid gears, worm gears, heavy dutybearings, planetary automatic shifts, and the like, necessitate the useof lubricants having superior load carrying properties. Lubricantspossessing superior load carrying properties which make them speciallyadapted for use under conditions of high pressure where the pressuresencountered are of such magnitude that the separation of gear teeth orbearing surfaces by an ordinary oil filament is not possible, arewell-known in the art as extreme pressure lubricants.

Extreme pressure lubricants are likewise important in cutting anddrawing operations where the oil must withstand the high pressuresencountered under those conditions of use. I

It is an object of this invention to provide an improved extremepressure lubricant which will give superior lubri cation to bearingsurfaces which are subjected to high pressures and/ or high rubbingvelocities. Another object of the invention is to provide a lubricantwhich will prevent gear teeth or bearing failure from scoring or gallingcaused by welding of small areas of the mating surface due to highpressure and high temperature.

I have found that the foregoing objects can be attained if there ispresent in the lubricating oil the reaction product obtained by heatinga mixture of sulfur-containing lead tallate, a chlorinated mixture ofhydrocarbons such as chlorinated paraflin Wax of high chlorine content,i. e., a chlorinated hydrocarbon oil or chlorinated paratfin wax ofabout 40% to 70% by weight of chlorine, oleic acid and said lubricatingoil at a temperature within the range of from about 225 F. to about 275F. for a period of at least hours and not more than about 120 hours, forexample, about 20 hours. This heating or aging step of the process maybe carried out in the presence of a small amount of water and preferablyin the presence of a small amount of water and a catalytic amount of afinely divided metal, selected from the class consisting of finelydivided iron and finely divided copper. I prefer iron or copper ofparticle size which passes through a #100 U. 8. standard screen.

I have been unable to determine the exact composition of the productobtained as a result of heating the above mixture of components.However, I believe that the ex cellent extreme pressure propertiesimparted to my novel composition are due to some component of thenatural tall oil which acts as a chlorine acceptor whereby a chlorinatedcomponent of the tall oil is formed, thereby pro viding a component tothe mixture which contains chlo- ICC line, received in the heating stepfrom the chlorinated wax component. This formation in situ of the activecomponent is brought about by the final heating step as indicatedhereinbelow. r a

More specifically, the process of preparing the lubricant involves thesteps of sulfurizing tall oil at a tempera ture of from about 300 F. toabout 350 F. with free sulfur to provide a sulfurized product containingfrom about 5% to 15% sulfur. This sulfurizing step is usually completein a'period of from 10m 15 hours. The reaction is completed to form asulfur-containing tall oil product which is non-corrosive to copper whenplaced in contact with copper at 250 F. for a period of 10 minutes. Thesulfur-containing tall oil products should contain about 5% to about15%, preferably about 8% to about 10% of sulfur. The sulfur-containingtall oil is then diluted with a lubricating oil, preferably ofrelatively high aromatic hydrocarbon content, of SAE grade #10, #20,#30, #40, #50, or #60, or blends of these, the

amount of diluent oil being equal by weight to the Weight of sulfurizedtall oil. The viscosities of lubricating oils of these grades fallwithin the range of from about 40 seconds to 200 seconds at 210 F.(SSU); .If desired,

' prior to adding the lubricating oil diluent to the sulfurized talloil, an amount of an oxide of lead such as litharge equal to about 20%by weight of the sulfurized tall oil to be reacted in forming the sulfurcontaining lead tallate, may be slurried in the diluent oil or the leadoxide 7 may be added to the mixture after the diluent is added to thesulfurized tall oil. The diluted sulfurized tall oil containing leadoxide is then heated at a temperature within the range of about 220 F.to about 230 F. to produce the sulfur-containing lead tallate component.To this diluted, heated mixture is then added a mixture of chlorinatedparaffin wax and oleic acid. If desired, this addition may be madesimultaneously with another portion of lubricating oil diluent. Themixture is stirred and held at a temperature within the range of F. toF. for a period of time sufiicient to provide a homogeneous mixture ofthe sulfur-containing lead tallate, oleic acid, chlorinated paraffinwax, and lubricating oil components. This homogeneous mixture is thenheated at a temperature within the range of 225 F. to about 275 F. for aperiod of at least 10 hours and not more than about '120 hours,preferably in the presence of a small amount of water, i. e., from about0.1% to about 1.0% of water based on the weight of the mixture, and inthe presence of from about 0.05% to about 0.5% by weight, based on theweight of the mixture, of a finely divided metal such as finely dividediron or finely divided copper. The product obtained according to thisprocedure may be diluted further with the lubricating oil following theheating, i. e., aging, step of the process to provide a finishedlubricating oil having the following approximate weight percentcomposition:

Lubricating oil (1060 SAE grade) 74-92 Sulfur-containing lead tallate5-10 Chlorinated paraffin wax (4070% C12) 1-'-10 Oleic acid 2-6 To thiscomposition may be added about two parts per million of a siliconeantifoaming agent.

The load-carrying capacity of extreme pressure lubricants may bedetermined by extreme pressure testing machines, such as the Timkentesting machine, described in the Journal of the Institute of Petroleum32, pp. 209-210 and 220-222 (1946). The mechanism and method of 1 use ofthe machine is well-known by those skilled in the Patented Dec. 6, 19 55art of testing petroleum products. In testing to determine the load alubricant will carry, a test is made using a load the oil will carryreadily and then successive tests are made using slightly increasedloads until failure occurs. The results of tests obtained in testingformulations illustrating my invention, formulations which containsulfur-containing lead soaps other'than sulfur-containing lead tallateand formulations containing the sulfurized lead tallate with chlorinatedparaffin wax component, with and without the presence of water and ironor copper catalyst are discussed hereinbelow and are shown in Tables Iand II below.

Example 1' One thousand grams of tall oil 1 were heated at a temperatureof 300 F. to 320 F. over a period of hours, during which period 100grams of flowers of sulfur were added in small increments. Thesulfurized oil was noncorrosive to copper and contained 9.14% sulfur.This product was then diluted with an equal weight of a Mid- Continentbase (acid-treated) SAE #10 grade oil and heated to a temperature of 220F. to 230 F. over a period of two hours, during which period 200 gramsof litharge were added to the stirred mixture. The oil-dilutedsulfur'containing lead tallate product, which was homogeneous, contained9.7% lead and 4.15% sulfur. To 450 grams of this product was then added120 grams of oleic acid and 180 grams of Chlorafin-42 and 2250 grams ofbase oil (acid treated SAE #50 grade) was added to give a lubricanthaving the following composition:

Percent Sulfur-containing lead tallate 7.5 Chlorafin-42 -c 6.0 Oleicacid 4.0 SAE #10 oil diluent 7.5 Base oil (SAE 50 grade) 75.0

The composition was stirred and held at a temperature of 140 F. to 160F. for a period of one hour to facilitate the production of ahomogeneous lubricant product. A silicone antifoam agent was added tothe extent of 2 parts by weight per million. The finished extremepressure lubricant contained 1.01% sulfur, 2.62% chlorine and 0.96%lead. It had a viscosity of 1293 seconds at 100 F. and 94.4 seconds(SSU) at 210 F.

The above product was tested for extreme pressure properties aftermodification in a series of heating experiments. The following sampleswere tested. Results are shown in Table I.

a. Base oil containing no extreme pressure agent.

b. Above non-heated formulation (of Example 1).

c. Formulation of b, mixed with 0.1% finely divided iron and 0.5% waterat room temperature.

11. Formula of b, mixed with water and finely divided iron as per c, andheated to 250 F. for less than /2 hour.

e. Formula of b, blown with air for 53 hours at 250 F.

1. Formula of b, heated at 250 F. for a period of 100 hours.

g. Formula of b, heated and stirred in presence of 0.5% water for periodof 100 hours.

- 11. Formula of b, stirred with iron and water and heated for period of100 hours.

i. Formula of b, stirred with 0.1% finely divided copper and 0.5% waterfor period of 100 hours.

i. Formula of b, stirred with 0.06% iron (as iron naphthenate) at roomtemperature for 100 hours.

k. Formula of j, stirred and heated for 100 hours at 250 F.

In addition to the above test samples results for which are shown inTable I, a formulation containing lead naph- A commercial grade of talloil, Indusoil (double distilled) marketed by Industrial Chemical SalesDivision, West Virginia Pulp and Paper Co.

11 Commercial chlorinated parafiin wax containing 40-42% chlorine(Chlorafin-42, product of Hercules Powder Com- P y thenate, sulfurizedsperm oil, Chlorafin and oleic acid corresponding to the followingcomposition:

Lead naphthenate Percent by weight 5 Sulfurized sperm oil do 5Chlorafin-42 do 6 Oleic acid do 4 Base oil (SAE grade) do 80 Antifoamagent p. p. m 2

was heated and stirred at 250 F. for a period of 100 hours in thepresence of 0.1% finely divided iron and 0.5% water. The non-heatedformulation passed" in the Timken test at 50 lbs. and failed at lbs. Theheated sample passed at 45 lbs. but failed at 50 lbs. Likewise, aformulation corresponding to the following composition:

Percent Sulfurized lead oleate 7.5 SAE #10 oil diluent 7.5 Chlorafin 6.0Oleic acid 4.0 Base oil (SAE 50 grade) 75.0

passed at 55 lbs. and failed at lbs. After aging in the presence of 0.1%finely divided iron and 0.5% water for 100 hours at 250 F. passed at 45lbs. and failed at 50 lbs.

TABLE I 'Ilmken Load Sample lbs. pass lbs. fail A series of heattreatments of the formulation contain ing the sulfurized lead tallate,Chlorafin and oleic acid prepared in Example 1 was made wherein theformulation was stirred and heated for different periods of time in thepresence of 0.1% by weight of finely divided iron and 0.5% by weight ofwater, in the absence of iron catalyst, and in the absence of water. Theresults of Timken tests of these samples are shown in Table II.

TABLE Il Aging study of sulfur-containing lead tallare formulationReferring to Tables I and II it can be seen that heating the formulationmade up of the sulfur-containing lead tallate, chlorinated wax, i. e.,Chlorafin, oleic acid, and lubricating oil at a temperature of 250 F.for a period of 24 to 96 hours raises the Timken value markedly. If thisheating operation is carried out in the presence of finely divided ironor copper as catalyst and in the presence of water, the improvement inTimken values is still greater.

Chlorinated compounds of various types are employed in extreme pressurelubricants. For example, products obtained by chlorinating parafiin waxare particularly adaptable in the present improved formulation andmethod of preparing the finished heated composition. These chlorinatedwax compositions are described in Encyclopedia of Chemical Technology,vol. 3, page 782, 1949 (The Interscience Encyclopedia, Inc., New- York3, N. Y.). While I prefer those chlorinated hydrocarbons containing fromabout 40% to 55% chlorine (by weight), which are usually liquid atambient temperatures, higher chlorine content chlorinated hydrocarbonscontaining up to about 70% chlorine may be used. Chlorine-containingcomponents are employed in accordance with my invention in sufficientamount to afford a total chlorine content in the lubricant of from about0.3% to about 8% and preferably from about 1% to about 3% by weight.

The tall oil used in the above example was, as indicated above, a sampleof Indusoil double-distilled tall oil of relatively high purity. Typicalrange of analyses of this grade is as follows:

While I prefer to use tall oil of grade equal to the above, I do notwish to be limited to the use of a highly purified grade of tall oilsince crude tall oil may be used in my formulation of improvedlubricant. However, the whole natural tall oil product must be used.Thus, I have prepared a synthetic tall oil containing 50% rosin acids,25% oleic acid, and 25% linoleic acid. The mixture sulfurized readilyand the lead soap was soluble in oil. When this sulfur-containing leadsoap was substituted for the sulfur-containing lead tallate in the aboveformulation of Example 1, the lubricant passes the Timken test at 60lbs. and failed at 65 lbs. However, aging the lubricant by heating at250 F. in the presence of finely divided iron and water failed toimprove the lubricant.

Having thus described my invention, I claim:

1. A composition suitable for use as a lubricating oil for thelubrication of metal to metal contact surfaces under conditions ofextreme pressure between said contact surfaces, which composition isobtained by heating at a temperature of 225 F. to 275 F. for at least 10hours and not more than 120 hours, a mixture consisting essentially of 5to parts by weight of sulfur-containing lead tallate slurried in 5 to 10parts by weight of a lubricating oil diluent having a viscosity withinthe range of about 40 to about 200 at 210 F. (SSU), 1 to 10 parts byWeight of a chlorinated parafiin wax of chlorine content Within therange of about 40 to about 70% by weight of chlorine and from about 2 toabout 6 parts by weight of oleic acid and adding suflicient lubricatingoil having a viscosity of about 40 to about 200 seconds at 210 F. (SSU)to provide a total of 100 parts by weight of said lubricating oilcomposition which sulfur-containing lead tallate is produced bysulfurizing tall oil with free sulfur to obtain a sulfur-containing talloil product containing 5 to by Weight of sulfur and non-corrosive tocopper and heating at a temperature of about 220 F. to about 230 F., aslurry of said sulfur-containing tall oil in said lubricating oildiluent in the presence of about by weight, based on the weight of saidsulfur-containing tall oil, of an oxide of lead suspended in saidlubricating oil acid is carried out in the presence of from about 0.05to a 0.2 part by weight, based on the weight of said mixture, of finelydivided metal selected from the class consisting of iron and copper.

3. A lubricating oil composition as described in claim 2, the totallubricating oil content of which is within the range of from about 74%to 92% by weight of'said lubricating oil composition.

4. The process for preparing a lubricant suitable for use in thelubrication of metal to metal contact surfaces under conditions ofextreme pressures between said contact surfaces, which process comprisesthe steps of (1) sulfurizing tall oil at a temperature of about 300 F.to 350 F. with free sulfur to contain from about 5% to about 15% ofsulfur, said sulfurized tall oil being noncorrosive to copper, (2)contacting at about 220 F. to 230 F. the product of step 1 with lithargeto produce a sulfur-containing lead tallate product, (3) commingling amixture of a chlorinated paraflin wax containing about 40% to about byweight chlorine, oleic acid, and a hydrocarbon oil diluent oflubricating oil viscosity range of from about 40 seconds to 200 secondsat 210 F. (SSU) with the product of step 2 at a temperature within therange of about F. to F. for a period of time suflicient to provide ahomogeneous mixture of sulfur-containing lead tallate, oleic acid,chlorinated paraflin wax, and lubricating oil diluent components and (4)heating the homogeneous mixture of step 3 at a temperature of about 225F. to about 275 F. for a period of at least 10 hours and not more thanabout 120 hours.

5. The process as described in claim 4, wherein the heating operation ofstep 4 is carried out in the presence of Water added to the homogeneousmixture in an amount within the range of about 0.1% to 1.0% by weight ofsaid mixture.

6. The process as described in claim 5 wherein the heating operation ofstep 4 is carried out in the presence of from about 0.05% to about 0.5%by weight, based on the weight of said mixture, of a finely dividedmetal selected from the class-consisting of iron and copper.

7. An extreme pressure lubricant consisting essentially References Citedin the file of this patent UNITED STATES PATENTS 2,175,491Stresen-Reuter Oct. 10, 1939 2,202,394 Morway May 28, 1940 2,472,503Minne June 7, 1949 OTHER REFERENCES Ind. Eng. Chem. 42, No. 9(1837-1841), 1950.

1. A COMPOSITION SUITABLE FOR USE AS A LUBRICATING OIL FOR THELUBRICATION OF METAL TO METAL CONTACT SURFACES UNDER CONDITIONS OFEXTREME PRESSURE BETWEEN SAID CONTACT SURFACES, WHICH COMPOSITION ISOBTAINED BY HEATING AT AT TEMPERATURE OF 225* F. TO 275* F. FOR AT LEAST10 HOURS AND NOT MORE THAN 120 HOURS, A MIXTURE CONSISTING ESSENTIALLYOF 5 TO 10 PARTS BY WEIGHT OF SULFUR-CONSISTING LEAD TALLATE SLURRIED IN5 TO 10 PARTS BY WEIGHT OF A LUBRICATING OIL DILUENT HAVING A VISCOSITYWITHIN THE RANGE OF ABOUT 40 TO ABOUT 200 AT 210* F. (SSU), 1 TO 10PARTS BY WEIGHT OF A CHLORINATED PARAFFIN WAX OF CHLORINE CONTENT WITHINTHE RANGE OF ABOUT 40 TO ABOUT 70% BY WEIGHT OF CHLORINE AND FROM ABOUT2 TO ABOUT 6 PARTS BY WEIGHT OF OLEIC ACID AND ADDING SUFFICIENTLUBRICATING OIL HAVING A VISCOSITY OF ABOUT 40 TO ABOUT 200 SECONDS AT210*F. (SSU) TO PROVIDE A TOTAL OF 100 PARTS BY WEIGHT OF SAIDLUBRICATING OIL COMPOSITION WHICH SULFUR-CONTAINING LEAD TALLATE ISPRODUCED BY SULFURIZING TALL OIL WITH FREE SULFUR TO OBTAIN ASULFUR-CONTAINING TALL OIL PRODUCT CONTAINING 5 TO 15% BY WEIGHT OFSULFUR AND NON-CORROSIVE TO COPPER AND HEATING AT A TEMPERATURE OF ABOUT220* F. TO ABOUT 230* F., A SLURRY OF SAID SULFUR-CONTAINING TALL OIL INSAID LUBRICATING OIL DILUENT IN THE PRESENCE OF ABOUT 20% BY WEITHT,BASED ON THE WEIGHT OF SAID SULFUR-CONTAINING TALL OIL, OF AN OXIDE OFLEAD SUSPENDED IN SAID LUBRICATING OIL DILUENT.